What does the term "homozygous" refer to regarding alleles?

• A. Having two different alleles for a trait
• B. Having two identical alleles for a trait
• C. Having one allele for a trait
• D. Having multiple alleles for a trait

Answer: (B)

The term "homozygous" specifically refers to an individual having two identical alleles for a particular trait. This means that both alleles on the homologous chromosomes are the same, which can influence the phenotype (observable characteristics) displayed by the organism. For example, if a plant has two alleles for flower color that are both "purple," it is described as homozygous for that trait because both alleles are identical.

Understanding this concept is crucial, as it differentiates homozygous individuals from heterozygous individuals, who possess two different alleles for a particular gene. Homozygosity can also have implications for inheritance patterns, as organisms that are homozygous for specific traits tend to produce offspring with predictable phenotypic outcomes when crossed with other homozygous organisms.